**Core Concept**
The Anganwadi workers use a growth chart to monitor the growth and development of children, specifically infants and preschoolers, as part of the Integrated Child Development Services (ICDS) program. This growth chart is crucial for early detection of growth abnormalities and timely intervention.

**Why the Correct Answer is Right**
The growth chart used by Anganwadi workers is the **World Health Organization (WHO) Growth Chart**, which is a standardized tool for monitoring growth in children. This chart takes into account the growth patterns of children from different regions and populations, making it a reliable and accurate tool for assessing growth. The WHO Growth Chart is widely used globally and is considered the gold standard for growth monitoring in children.

**Why Each Wrong Option is Incorrect**
**Option A:** The **Centers for Disease Control and Prevention (CDC) Growth Chart** is primarily used in the United States and is not the standard growth chart used by Anganwadi workers in India.
**Option B:** The **Indian Academy of Pediatrics (IAP) Growth Chart** is a customized growth chart for Indian children, but it is not the standard growth chart used by Anganwadi workers.
**Option C:** The **Ashoka Narain Growth Chart** is not a widely recognized or standard growth chart used by Anganwadi workers.

**Clinical Pearl / High-Yield Fact**
Growth monitoring is an essential component of early childhood development, and the WHO Growth Chart is a crucial tool for detecting growth abnormalities and ensuring timely intervention.

**Correct Answer: C. World Health Organization (WHO) Growth Chart.**